Detachable aneurysm neck bridge

ABSTRACT

In one embodiment, a neck bridge for bridging the neck of an aneurysm includes a junction region, a number of radially extending array elements attached to the junction region, and a cover attached to one or both of the junction region and an array element. The array elements are configured to be positioned within the aneurysm after the neck bridge is deployed from a delivery device. In a second embodiment, the neck bridge includes a junction region and a braided or mesh-like structure secured to the junction region. The braided or mesh-like structure is made from an elastic material.

RELATED APPLICATION DATA

[0001] This application is a continuation-in-part of co-pending U.S.patent application Ser. No. 09/548,644 filed Apr. 13, 2000, which is acontinuation of U.S. patent application Ser. No. 09/148,411 filed Sep.4, 1998, now abandoned, the disclosures of which are expresslyincorporated by reference herein.

FIELD OF THE INVENTION

[0002] The inventions disclosed herein pertain to systems, apparatus,and methods for treating aneurysms, and more specifically, to systems,apparatus, and methods for bridging a neck of an aneurysm.

BACKGROUND

[0003] Various implantable medical devices have been developed fortreating a number of ailments associated with body lumens. Inparticular, occlusive devices have been proven useful in fillingvascular aneurysms, which are formed due to a weakening in the wall ofan artery. Vascular aneurysms are often the site of internal bleedingand stroke. A variety of different embolic agents are known to be, atleast arguably, suitable for treatment of vascular aneurysms by fillingthem to prevent further vessel wall weakening or rupture. Use of theseagents are commonly known as “artificial vaso-occlusion.”

[0004] Over the past few years, advancements in the artificial occlusionof vessels and aneurysms have included the delivery and implantation ofmetal coils as vaso-occlusive devices. Implantable metal coils that areuseful as artificial occlusion devices in vasculature lumens oraneurysms are herein referred to as “vaso-occlusive coils.”Vaso-occlusive coils are typically constructed of a wire made of a metalor metal alloy wound into a helix. Such vaso-occlusive coils aretypically manufactured to assume a certain shape upon discharge of thedevice from the distal end of the catheter into a treatment site. Avariety of such vaso-occlusive coils are known. For instance, U.S. Pat.No. 4,994,069, issued to Ritchart et al., discloses a flexible,preferably coiled wire for use in small vessel vaso-occlusion. Unlikevaso-occlusive coils used prior to that time, Ritchart et al. disclosesusing a coil that is relatively soft and is delivered to the site usinga pusher within a catheter lumen. Upon discharge from the deliverycatheter, the coil may undertake a number of random or pre-determinedconfigurations useful to fill the site.

[0005] Known vaso-occlusive coils may be used for filling relativelysmall vessel sites, e.g., 0.5-6.0 mm in diameter. The coils themselvesare described as being between 0.254 and 0.762 mm in diameter. Thelength of the wire making up the vaso-occlusive coil is typically 15 to20 times the diameter of the vessel to be occluded. The wire used tomake up the coils may be, for instance, 0.051 to 0.152 mm in diameter.Tungsten, platinum, and gold threads or wires are typically preferred.These coils have a variety of benefits, including the fact that they arerelatively permanent, they may be easily imaged radiographically, theymay be located at a well defined vessel site, and they can be retrieved,if necessary.

[0006] In addition to the various types of known space fillingmechanisms and geometries of vaso-occlusive coils, other particularizedfeatures of coil designs, such as mechanisms for their delivery throughcatheters and implanting them in a desired occlusion site, are well knowin the art. Examples of known vaso-occlusive coils categorized by theirdelivery mechanisms include pushable coils, mechanically detachablecoils, and electrolytically detachable coils.

[0007] One example of a “pushable coil” is disclosed in Ritchart et al.,discussed above. Pushable coils are commonly provided in a cartridge andare pushed or “plunged” from the cartridge into a lumen of a deliverycatheter. A pusher (e.g., a wire or a pressurized fluid) advances thepushable coil through and out of the delivery catheter lumen, into thedesired occlusion site.

[0008] Mechanically detachable vaso-occlusive coils are typicallyintegrated with a pusher rod and are mechanically detached from thedistal end of that pusher after exiting a delivery catheter. Examples ofsuch mechanically detachable vaso-occlusive coils are found in U.S. Pat.No. 5,261,916 to Engelson and U.S. Pat. No. 5,250,071 to Palermo.

[0009] Examples of electrolytically detachable vaso-occlusive coils maybe found in U.S. Pat. Nos. 5,122,136 and 5,354,295 issued to Guglielmiet al. In these devices, the vaso-occlusive portion of the assembly isattached to a pusher via a small, electrolytically severable joint. Theelectrolytically severable joint is eroded by the placement of anappropriate voltage on the core wire.

[0010] As noted above, aneurysms present a particularly acute medicalrisk due to the dangers of potential rupture of the thin vascular wallinherent in such aneurysms. Occlusion of aneurysms by use ofvaso-occlusive coils without occluding the adjacent artery is a specialchallenge and is a desirable method of reducing such risk of rupture.Vaso-occlusive devices may be placed in an aneurysm in a mannerdescribed in U.S. Pat. No. 4,739,768 issued to Engelson. In particular,a microcatheter is initially steered into or adjacent to the entrance ofan aneurysm, typically aided by the use of a steerable guidewire. Thewire is then withdrawn from the microcatheter lumen and replaced by oneor more vaso-occlusive coils, which are then advanced through and out ofthe microcatheter, and into the aneurysm.

[0011] However, after, or perhaps during delivery of a coil into theaneurysm, there is a risk that a portion of the coil might migrate outof the aneurysm entrance zone and into the feeding vessel. The presenceof the coil in that feeding vessel may cause a highly undesirableocclusion there. Also, there is a risk that the blood flow in the vesseland aneurysm may induce movement of the coil farther out of theaneurysm, resulting in a more developed embolus in the feeding vessel.

[0012] One type of aneurysm, commonly known as a “wide neck” aneurysm,is known to present particular difficulty in the placement and retentionof vaso-occlusive coils, because vaso-occlusive coils lackingsubstantial secondary shape strength may be difficult to maintain inposition within an aneurysm no matter how skillfully they are placed.Wide neck aneurysms are herein referred to as aneurysms of vessel wallshaving a neck or “entrance zone” from the adjacent vessel, wherein theentrance zone has a diameter that either: (1) is at least 80% of thelargest diameter of the aneurysm; or (2) is clinically observed to betoo wide effectively to retain commercially available vaso-occlusivecoils that are deployed using the techniques discussed above.

[0013] Certain techniques have been developed in order to deal with thedisadvantages associated with embolic material migration into the parentvessel. One such technique, commonly referred to as flow arrest,involves temporarily occluding the parent vessel proximal of theaneurysm, so that no blood flow occurs through the parent vessel until athrombotic mass has formed in the sac of the aneurysm. While thistechnique helps reduce the tendency of the embolic material to migrateout of the aneurysm sac, a thrombotic mass can still dissolve throughnormal lysis of blood. Also, occluding the parent vessel may not preventall embolic material migration into the parent vessel. Further, incertain cases, it is highly undesirable to occlude the parent vesseleven temporarily. Thus, a flow arrest technique is, at times, noteffective or even not available as a treatment option.

[0014] Another approach to occlude a wide neck aneurysm is described inU.S. Pat. No. 6,168,622 (“the '622 patent”), which describes avaso-occlusive device with a secondary shape having a bulbous bodyportion and an anchor. The bulbous body portion is deployed within theaneurysm while the anchor is set just outside of the aneurysm, coveringthe aneurysm's neck or entrance zone. As described in the '622 patent,the device may be integrally formed from a tube—clamped at both ends—ofbraided Nickel-Titanium (NiTi) wires. The bulbous body functions toocclude the aneurysm, while the anchor covers the entrance zone. In somecases, it may still be desirable to deploy vaso-occlusive coils withsuch a device, but the bulbous body of the vaso-occlusive device may notprovide much space within the aneurysm to allow for insertion anddeployment of coils.

SUMMARY OF THE INVENTION

[0015] In accordance with one aspect of the present invention, a neckbridge for bridging across a neck of an aneurysm comprises a junctionregion, one or more array elements attached to the junction region, anda cover attached to the junction region. The cover may alternatively beattached to the array elements, or to both the array elements and thejunction region. By way of non-limiting examples, the array element mayhave a shape of a loop, a substantially rectilinear shape, or acurvilinear shape. In preferred embodiments, the array element may bestretched into a delivery shape when positioned within a lumen of adelivery catheter, and assumes an unfolded configuration when unconfinedoutside the lumen. Suitable materials for construction of the arrayelement include, but are not limited to, elastic and super elasticmaterials, such as Nitinol.

[0016] By way of non-limiting examples, the cover may be a fabric, awoven or non-woven mesh, or other sheeting or planar structure. In oneembodiment, the cover may comprise a braided or mesh-like structure thatincludes a plurality of loops, each loop comprising a fiber having endssecured to the junction region. In preferred embodiments, the coverfolds into a low profile structure when positioned within the deliverycatheter lumen, and is unfolded by the array elements when the arrayelements assume an unfolded configuration outside the lumen.

[0017] Embodiments of the neck bridge may be detachably coupled to adistal end of a delivery member, a core wire, or similar structure viaan electrilytically severable joint or a mechanical joint.

[0018] In accordance with another aspect of the present invention, aneck bridge for bridging across a neck of an aneurysm comprises ajunction region and a braided (or “mesh-like”) structure attached to thejunction region. The braided structure is preferably made of an elasticor super-elastic material, and is capable of being stretched into adelivery shape when positioned in a lumen of a delivery catheter. Thebraided structure assumes an unfolded configuration when unconfinedoutside the delivery lumen. In one embodiment, the braided structurecomprises a plurality of loops, each loop comprising a fiber having endssecured to the junction region. In another embodiment, the junctionregion includes a first portion and a second portion, and the braidedstructure comprises a plurality of loops, each loop comprising a fiberhaving a first end secured to the first portion, and a second endsecured to the second portion.

[0019] Other embodiments of the neck bridge in accordance with thesecond aspect of the invention are also described. By way ofnon-limiting examples, the neck bridge may optionally be detachablycoupled to a distal end of a delivery member, a core wire, or similarstructures via an electrilytically severable joint or a mechanicaljoint.

[0020] Other aspects, features, and embodiments of the invention aredescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings illustrate the design and utility of preferredembodiments of the present invention, in which similar elements arereferred to by common reference numerals. It should be understood thatthese drawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope.

[0022]FIG. 1 is a cross sectional plan view of an aneurysm treatmentsystem including a neck bridge comprising an array of elements inaccordance with a preferred embodiment of the invention;

[0023]FIG. 2 is a partial cross sectional view of a distal end of thesystem of FIG. 1;

[0024]FIG. 3 is a partial cross sectional view of a variation of thedistal end of the system of FIG. 1, particularly showing a junctionregion of the neck bridge coupling to a distal tip of an inner tubularmember;

[0025]FIG. 4 is a partial cross sectional view of the distal end of theinner tubular member shown in FIG. 3, particularly showing the neckbridge assuming a delivery shape;

[0026]FIG. 5 is a top view of the neck bridge of FIG. 1;

[0027]FIG. 6 is a top view of a variation of the neck bridge,particularly showing a cover having a plurality of loops;

[0028] FIGS. 7A-7C are side views of further variations of the neckbridge;

[0029]FIG. 8 is a top view of a still further variation of the neckbridge, particularly showing the array elements having substantiallyrectilinear shapes;

[0030]FIGS. 9A and 9B show another variation of the neck bridge,particularly showing the array elements having different unfoldedconfigurations;

[0031]FIGS. 10A and 10B show yet another variation of the neck bridge,particularly showing the array elements having upright loop shapes;

[0032]FIG. 11 is a side view of a still another variation of the neckbridge, particularly showing the neck bridge having a pair of collarscoupled to control wires;

[0033]FIG. 12 is a top view of the neck bridge of FIG. 11 in a deployed(i.e., non-constrained) configuration;

[0034]FIG. 13 is a top view of yet another variation of the neck bridge,particularly showing the neck bridge having a braided structure;

[0035]FIGS. 14A and 14B show a delivery shape and an unfoldedconfiguration, respectively, of the neck bridge of FIG. 13;

[0036]FIGS. 15A and 15B show a variation of the delivery shape and theunfolded configuration, respectively, of the neck bridge of FIG. 13;

[0037]FIG. 16 is a further variation of the neck bridge, particularlyshowing the junction region of the neck bridge coupled to a wall sectionof the inner tubular member;

[0038]FIG. 17 is a still further variation of the neck bridge,particularly showing the junction region of the neck bridge coupled to acore wire by a severable joint;

[0039] FIGS. 18A-18E show a procedure for introducing an embodiment ofthe neck bridge, along with a vaso-occlusive device, into an aneurysm;

[0040]FIG. 19A shows a side view of an embodiment of a neck bridge incombination with an “anchor” adapted to be placed within an aneurysm;

[0041]FIG. 19B is a top view of the neck bridge of FIG. 19A; and

[0042]FIG. 19C shows a placement of the neck bridge depicted in FIG. 19Awithin an aneurysm.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] The disclosed invention relates to devices and procedures forstabilizing the position and, in some instances, the structure ofvaso-occlusive devices placed in a target occlusion site, usually ananeurysm. Use of the retaining devices and neck bridges disclosed hereinreduce the potential migration of vaso-occlusive devices (e.g.,helically wound coils) from target occlusion sites, by forming at leasta partial barrier at the entrance zone to the aneurysm, i.e., where theaneurysm meets a feeding vessel.

[0044]FIG. 1 shows an aneurysm treatment system 100, which includes ananeurysm neck bridge 106 constructed in accordance with a preferredembodiment. The aneurysm treatment system 100 also includes a tubulardelivery catheter 102, and an inner elongated tubular member 104slidable within the tubular delivery catheter 102. The aneurysm neckbridge 106 is removably coupled to a distal end 107 of the elongatedtubular member 104 via an electrolytically severable joint 122, and isconfigured to be placed within an aneurysm sac or directly across a neck(i.e., in between the tissue defining the neck) of an aneurysm. Thesystem 100 further includes a vaso-occlusive device 108 that isdeliverable via the inner tubular member 104. The vaso-occlusive device108 is coupled to a core wire 110 via another electrolytically severablejoint 130. The severable joints 122 and 130 are of a scale that cannoteasily be seen in FIG. 1 and are depicted in greater clarity in FIG. 2.

[0045] Schematically, the electrolytically severable joints 122 and 130are configured to electrically couple to first and second power supplies112 and 114, respectively, which are used to deliver current to severethe respective joints in a well known manner. The severance of theseverable joints 122 and 130 releases the aneurysm neck bridge 106 andthe vaso-occlusive device 108, respectively, at the site. Alternatively,a single power supply may be used to supply current for detachment ofthe vaso-occlusive device 108 and the aneurysm neck bridge 106.

[0046]FIG. 2 is a partial cross section of a distal end of the system100. The distal end 103 of delivery catheter 102 carries a radio-opaquemarker 116 to assist navigating the distal end 103 through avasculature. The inner tubular member 104 also carries a radio-opaquemarker 118. In alternate embodiments, the inner tubular member 104 mayhave a shape other than that shown in FIG. 2. For example, the innertubular member 104 may have an angle or a curvilinear shape. Preferably,the inner tubular member 104 is malleable or heat settable so that aphysician or operator can create a desired shape at the time the system100 is used.

[0047] A conductor wire 120 is provided for conducting current from thefirst power supply 112 to the electrolytically detachable joint 122. Theaneurysm neck bridge 106 includes a junction region 124, which isdetachably coupled to a distal end 107 of the inner delivery member 104.The junction region 124 may include an opening 128 (shown in FIG. 5),and may have a shape of a tubular member or a ring. The junction region124 preferably fits around the inner tubular member 104 in a loosemanner, and is maintained in position only by the electrolytic joint122. In alternate embodiments, the exterior profile of the junctionregion 124 can vary from the circular shape shown in the illustratedembodiment. Examples of variations in the shape of the junction region124 are shown and described herein.

[0048] The severable joint 122 is preferably created by insulating aportion of the conductor wire 120. For example, a portion of theconductor wire 120 may be insulated with an electrical insulator whichis not susceptible to dissolution via electrolysis in blood or otherionic media, leaving the un-insulated portion of the conductor wire 120susceptible to electrolytic dissolution. The electrical insulator may bethe wall of the tubular member 104, as shown in FIG. 2, oralternatively, it may be a coating placed over the conductor wire 120.Suitable coatings include insulating materials, such aspolyfluorocarbons (e.g., Teflon), polyurethane, polyethylene,polypropylene, polyimides, and other suitable polymeric materials. Itwill also be apparent that the sacrificial joint 122 is more susceptibleto electrolysis than any other element of the device located near thatjoint 122. In use, current supplied by the first power supply 112 passesto the electrolytically severable joint 122, typically with thecooperation of an external return electrode pad (not shown) placed on askin of a patient to complete the circuit. Passage of current throughthe electrolytically severable joint 122 causes the joint 122 to severe,thereby de-coupling the neck bridge 106 from the tubular member 104.Further information regarding the construction, placement, and otherphysical details of electrolytically severable joints used may be foundin U.S. Pat. Nos. 5,234,437, 5,250,071, 5,261,916, 5,304,195, 5,312,415,and 5,350,397, the disclosures of which are expressly incorporated byreference herein. It will be appreciated that mechanical joints, andother types of detachable joints known in the art for placing occlusivedevices in aneurysms may alternatively be used to couple the neck bridge106 to the tubular member 104. Examples of such mechanical joints may befound in U.S. Pat. No. 5,234,437, to Sepetka, U.S. Pat. No. 5,250,071 toPalermo, U.S. Pat. No. 5,261,916, to Engelson, U.S. Pat. No. 5,304,195,to Twyford et al., U.S. Pat. No. 5,312,415, to Palermo, and U.S. Pat.No. 5,350,397, to Palermo et al, the disclosures of which are expresslyincorporated herein by reference.

[0049] As shown in FIG. 2, because the neck bridge 106 is coupled to thetubular member 104 in a way that does not obstruct the distal opening131 of the tubular member 104, the vaso-occlusive device 108 may bedelivered via the inner tubular member 104. In the illustratedembodiment, the vaso-occlusive device 108 is detachably coupled to adistal end of the core wire 110 by the electrolytically severable joint130, which is formed by insulating a proximal portion of the core wire110 by an insulating layer 128. As noted above, delivery ofvaso-occlusive devices using an electrolytically severable joint is wellknown in the art. Alternatively, the vaso-occlusive device 108 may bedelivered by using a pusher or plunger, the distal advancement of whichwithin the inner tubular member 104 pushes the vaso-occlusive device 108out from the distal end of the inner tubular member 104. Other methodsof delivering the vaso-occlusive device 108 known in the art may also beused.

[0050]FIG. 3 shows another variation of the neck bridge 106. Unlike thepreviously shown embodiment, in which the junction region 124 of theneck bridge 106 is configured to fit around the distal end 107 of theinner tubular member 104, the junction region 124 of the neck bridge 106of FIG. 4 is distal to the distal end 107 of the tubular member 104, andis configured to couple to a distal end 107 of the inner tubular member104 via the severable joint 122. In this variation, the cross sectionaldimension of the junction region 124 is substantially the same as thecross sectional dimension of the inner delivery member 104 to form asubstantially continuous outer surface. Vaso-occlusive devices 108exiting the distal end 107 of the tubular member 104 can be delivered toan aneurysm by passing through the opening 128 of the junction region124, as discussed previously. The distal end 107 of the inner tubularmember 104 may further include a Teflon liner or an extension (notshown) coupled to the interior surface of the inner tubular member 104,such that fluid (e.g., an embolic agent) can be delivered through theopening 128 of the junction region 124 without escaping into the gapbetween the tip of the inner tubular member 104 and the junction region124.

[0051] The neck bridge 106 includes one or more radially expanding arrayelements or wires 126 attached to the junction region 124, and a cover127 attached to the junction region 124. In alternate embodiments, thecover 127 may also be secured to the array elements 126. In furtheralternate embodiments, the cover 127 may be attached to both the arrayelements 126 and the junction region 124. Upon placement in an aneurysm,the array elements 126 together with the cover 127 spread to the generalshape shown in FIG. 2. In the illustrated embodiment, each of the arrayelements 126 is a wire loop or ribbon rim. The number of array elements126 may vary between embodiments, depending on factors such as the sizeof an aneurysm, the width of the tubular delivery catheter 102, and thethickness of the wire making up the array elements 126. Before the neckbridge 106 is deployed to a target site, the neck bridge 106 resideswithin a lumen 132 of the delivery catheter 102, and it is generallystretched to assume and maintain the shape of the lumen 132 as shown inFIG. 4. The cover 127 is folded into a low profile when positioned inthe lumen 132. When the neck bridge 106 is pushed from the distal end ofthe delivery catheter 102, the array elements 126 assume their so-called“unfolded” shapes or configurations, thereby unfolding the cover 127.

[0052] The array elements 126 may be required to undertake relativelysignificant changes in shape during deployment of the neck bridge 106.To undertake such stress, it is usually preferable that the arrayelements 126 be produced of a material such as a super-elastic alloy.Super-elastic or pseudoelastic shape recovery alloys are well known inthis art. For instance, U.S. Pat. Nos. 3,174,851; 3,351,463; and3,753,700 each describe one of the more well known super-elastic alloys,known as Nitinol. These alloys are characterized by their ability to betransformed from an austenitic crystal structure to a stress-inducedmartensitic (SIM) structure at certain temperatures and then to returnelastically to the austenitic shape when the stress is removed. Thesealternating crystal structures provide the alloy with its super-elasticproperties.

[0053] The above described alloys are especially suitable because oftheir capacity to recover elastically, and almost completely to anunfolded configuration once a bending stress is removed. Typicallyduring use, these alloys suffer little permanent plastic deformation,even at relatively high strains. This ability allows the neck bridge 106to undertake substantial bends while residing within the lumen 132 ofthe tubular delivery catheter 102 and while passing through avasculature. In spite of this bending, the neck bridge 106 returns toits original shape, i.e., unfolded configuration, without retaining anysubstantial permanent kinks or bends once deployed from the lumen 132.

[0054] Of the super-elastic alloys currently available, the preferredmaterial is 50.6.+−0.2% nickel with most of the remainder beingtitanium. Up to about 5% of the alloy may be a member of the iron groupof metals, particularly chromium and iron. The alloy is preferred to notcontain more than about 500 parts per million of oxygen, carbon, ornitrogen. The transition temperature of this material is notparticularly important, but it should be reasonably below the typicaltemperature of the human body so as to allow it to be in its austeniticphase during use. The wires or ribbons making up the various arrayelements 126 preferably have a diameter less than about 0.010 inches.These super-elastic alloys are not always sufficiently visible underfluoroscopy as it is used in the human body. Consequently it may bedesirable to add a radio-opacity covering to the array elements 126.Radio-opaque metals such as gold and platinum are well known.Radio-opaque metals may be added to the array elements 126 by plating orby wrapping the array element 126 in a radio-opaque wire or ribbon, asis known in the art. Alternatively, one or more radio-opaque markers maybe secured to the array elements 126, for example at a perimeter of theneck bridge defined by the array elements 126.

[0055] Other metals may also be appropriate for construction of thearray elements 126. Such metals include stainless steels and otherhighly elastic, if not super-elastic, alloys. Polymeric materials whichare somewhat easier to work with in forming a device may also be usedfor construction of the array elements 126. Polymeric materials aresomewhat easier to work with in forming a device. Such polymericmaterials may include members from the group of polyethylene,polypropylene, polytetraflouroethylene, various Nylons, and the like.Suitable polymers may also include most biocompatible materials, whichmay be made into fibers, including thermoplastics, e.g., polyesters suchas polyethyleneterephthalate (PET) especially Dacron; polyamidesincluding Nylons; polyolefins such as polyethylene, polypropylene,polybuylene, their mixtures, alloys, block and random copolymers;polyglycolic acid; polylactic acid; fluoropolymers(polytetrafluoro-ethylene), or even silk or collagen.

[0056]FIG. 5 shows a top view of the neck bridge 106. As shown in FIG.5, the cover 127 is unfolded to have a substantially continuous surfacewhen the array elements 126 assume their unfolded configurations. Thecover 127 may be a fabric, a woven or non-woven mesh, or other sheetingor planar structure. Although the array elements 126 are each preferablyof a form that retains a large measure of elasticity after having beenbent, the cover 127 may be less elastic. The cover 127 may be made froma variety of materials such as polymers, nylons, and polyester. Thesematerials do not provide substantial strength to the cover 127, so as toallow the device to be readily folded into a low profile and placed intothe delivery catheter lumen 132 without adding unnecessary stiffness.The sole function of the cover 127 is to remain an implantedvaso-occlusive device in an aneurysm. The function of the array elements126 is to maintain the structural integrity of the neck bridge device asit is situated within an aneurysm. Alternatively, the cover 127 may bemade to have a similar elasticity as the array elements 126. Therefore,any of the materials discussed previously with reference to the arrayelements 126 may also be suitable for construction of the cover 127.Other materials suitable for construction of the cover 127 includeDacron (polyethyleneterephthalate), collageneous materials,polyluorocarbons, combinations thereof, and other vascular graftmaterials. Fibrous materials, such as polyglycolic acid, wool, orcotton, may also be used.

[0057]FIG. 6 shows a variation of the cover 127, which has a braided ormesh-like structure. In the illustrated embodiment, the neck bridge 106includes six array elements 126 attached to the cover 127. The cover 127includes a plurality of loops 210, each of which formed by securing endsof a-fiber to the junction region 124. The loops 210 may overlap oneanother, or alternatively, be inter-woven with each other, to form thecover 127. It should be noted that the shape of the loop 210 is notlimited to that shown in the illustrated embodiment. Furthermore, thecover 127 may have different braided patterns than those shown herein.

[0058] In each of the above-described embodiments of the neck bridge,the cover 127 may be placed at a top side of the array elements 126(FIG. 7A), a bottom side of the array elements 126 (FIG. 7B), or it maycover both sides of the array elements 126 (FIG. 7C). In the embodimentshown in FIG. 7C, the neck bridge may further include a disk (not shown)placed between the bottom and top surfaces of the cover 127 for reducingthe porosity of the neck bridge.

[0059] Notably, the shape of the cover 127 is not limited to thecircular shape shown in the previously discussed embodiments. The cover127 can have other shapes, such as an elliptical or rectangular shape(FIG. 8).

[0060] Generally, as with the embodiments shown in FIGS. 7A and 7C, thecover 127 is not required to be directly secured to any of the arrayelements 126. Rather, the array elements 126 exert a bearing and/orfrictional force on the cover 127 when they assume an unfoldedconfiguration. However, the cover 127 may optionally be secured to thearray elements 126 at one or more various points. The securing may beaccomplished using a glue, epoxy, heat bond, or other suitableadhesives, depending upon the materials from which the respective cover127 and array elements 126 are made. By way of further example, thecover 127 may also be secured to the array elements 126 by sewing themtogether using a thread. Securing the cover 127 to the array elements126 may assist the array elements 126 in unfolding the cover 127 into adesired shape as the array elements 126 assume their unfoldedconfigurations. Alternatively, the array elements 126 may be embeddedwithin the cover 127, or inter-woven with the cover 127.

[0061] It should be noted that the shape of the individual array elementis not limited to the loop shape shown in the previous embodiments, andthat the array element 126 may have other shapes as well. FIG. 8 shows avariation of the array element 126 that has a substantially rectilinearprofile. As shown in the illustrated embodiment, the array elements mayoptionally have blunted tips to avoid trauma to the arteries in whichthey are placed. The array elements 126 may also have other shapes aswell. In the embodiment of FIG. 8, the cover 127 has a rectangularshape, as previously noted.

[0062] The manner in which the array elements fold or bend whenpositioned within the lumen of a tubular delivery member is not limited.By way of illustration, FIGS. 9A and 9B show another variation of theneck bridge, wherein the array elements 126 are folded in a manner thatis different from that shown in FIG. 4. In the embodiment of FIGS. 9Aand 9B, each of the array elements 126 has an end 211 coupled to a tip212. The tip 212 includes a radio-opaque marker 216. The tip 212 alsoincludes an opening 217 through which a vaso-occlusive device orocclusion fluid may be delivered. The array element 126 has a midportion that flares outward while maintaining the end 211 of the arrayelement 126 in close proximity to an axis 214 of the junction region124. The array elements 126 are stretched to the delivery shapes shownin FIG. 9A when positioned within the lumen 132 of the delivery catheter102, and assume the unfolded configurations shown in FIG. 9B whenunconfined outside the delivery catheter 102. The array elements 126 canalso have curvilinear shapes or other unfolded configurations, so longas the array elements 126 unfold the cover 127 once deployed outside thelumen 132 of the delivery catheter 102.

[0063]FIGS. 10A and 10B, respectively show side and top views of anothervariation of the neck bridge 106, wherein the array elements 126 haveupright loop shapes. Although the array elements 126 are shown attachingto an interior surface of the junction joint 124, the array elements 126may also be secured to the ends or the side of the junction joint 124.In the illustrated embodiment, the array elements 126 wrap around aperimeter of the cover 127 such that the cover 127 is between the endsof the wires defining the loop shape array elements 126. Alternatively,as shown by the dashed-lines, the cover 127 may also be placed at abottom side of the array elements 126.

[0064] The array elements 126 may also be deployed using mechanicalmethods. FIG. 11 shows another variation of the neck bridge 220 that isdelivered on the exterior of a delivery member 221. This variationincludes a number of radially extending array elements 222 which arejoined at their outer ends. The radially extending array elements 222are joined by a cover 224 which also may be scrim-like. The arrayelements 222 are joined to a pair of collars 226 that slide on thedelivery member 221 and are controlled by one or more control wires 228.Each of the control wires 228 may have a releasable joint 229, desirablyan electrolytically severable joint, as discussed previously. Duringdelivery of the neck bridge 220, the array elements 222 lie generallyagainst the delivery member 221. During deployment, the control wires228 are axially manipulated to extend the radially extending arrayelements 222 into the deployed shape depicted in FIG. 12.

[0065] In the previously discussed embodiments, the neck bridge includesone or more array elements attached to the cover. However, the arrayelements may not be required. FIG. 13 shows a variation of the neckbridge which includes a junction region 202 and a braided or mesh-likestructure 230 secured to the junction region 202. The braided structure230 may carry a radio-opaque marker (not shown), or be plated or coatedwith a radio-opaque material. The braided structure 230 is preferablymade from an elastic material, such as Nitinol. However, any of thematerials discussed previously with reference to the array element 216may also be suitable for construction of the braided structure 230. Theadvantage of making the braided structure 230 using elastic material isthat the braided structure 230 can assume an unfolded shape without thehelp of the array elements. The braided structure 230 may also be madefrom a radio-opaque material. In the illustrated embodiment, the braidedstructure 230 includes a number of loops 232, each of which formed bysecuring ends of a fiber to the junction region 202. However, thebraided structure 230 can have other woven or non-woven patterns aswell. FIGS. 14A and 14B show that the braided structure 230 can assume adelivery shape by bending the loops 232 such that the portions of theloops 232 defining the periphery of the braided structure 230 are distalto both ends of the fibers making up the loops 232.

[0066]FIGS. 15A and 15B show a variation of the neck bridge of FIG. 13.As shown in the embodiment, a first end of the fiber making up each ofthe loops 232 is secured to a first portion 202 a of the junction region202, and a second end of the fiber making up each of the loops 232 issecured to a second portion 202 b of the junction region 202. Whenresiding within the delivery catheter 102, the braided structure 230 isstretched or bent into a delivery shape such as that shown in FIG. 15A.When the neck bridge is deployed outside the delivery catheter 102, thefirst portion 202 a and the second portion 202 b of the junction regionmove closer to each other, and the portion of the loop 232 near themid-section 234 of the loop 232 becomes the periphery of the braidedstructure 230. It should be noted that the manner in which the braidedstructure 230 is folded or deployed should not be limited to theexamples described previously, and that other methods of folding ordeploying the braided structure 230 can also be used.

[0067] In all of the previously described embodiments, the junctionregion includes the opening 128 through which a vaso-occlusive device108 may be delivered. However, the opening 128 is optional. FIG. 16shows a cross sectional view of a variation of the junction region 124that does not have the opening 128. In the illustrated embodiment, thejunction region 124 is detachably secured to a wall section of the innertubular member 104 by an electrolytically severable joint 240. Thevaso-occlusive device 108 may also be delivered via the inner tubularmember 104, as discussed previously.

[0068] The neck bridge 126 may be detachably coupled to other structuresinstead of the inner tubular member 104 described previously. FIG. 17shows a cross sectional view of a neck bridge 126 that is detachablycoupled to a core wire 250 by an electrolytically severable joint 252. Aproximal portion of the core wire 250 is insulated by an insulatinglayer 254 to form the severable joint 252. In this case, the deliverycatheter 102 is used to deliver both the neck bridge 106 and thevaso-occlusive device 108.

[0069] The method of using the previously described neck bridges willnow be discussed with reference to FIGS. 18A-18E. First, the deliverycatheter 102 is inserted into the body of a patient. Typically, thiswould be through a femoral artery in the groin. Other entry sitessometimes chosen are found in the neck and are in general well known byphysicians who practice these types of medical procedures. The deliverycatheter 102, which may be a microcatheter or a sheath, may bepositioned so that the distal end of the delivery catheter 102 isappropriately situated, e.g., near the neck of an aneurysm 306 to betreated. (FIG. 18A) The placement of the delivery catheter 102 may beassisted by the use of guide wire and/or a radio-opaque marker, as areknown in the art.

[0070] A neck bridge 308, which is representative of any of theembodiments of the neck bridge discussed previously, is carried withinthe delivery catheter 102 before it is deployed. While positioned withinthe delivery catheter 102, the neck bridge 308 is stretched into adelivery shape. If the neck bridge 308 is coupled to the inner tubularmember 104, the neck bridge 308 may be deployed by retracting thedelivery catheter 102 relative to the tubular member 104, or byadvancing the tubular member 104 relative to the delivery catheter 102.Alternatively, if the neck bridge 308 is coupled to the core wire 250,such as that shown in FIG. 17, the neck bridge 308 may be deployed byretracting the delivery catheter 102 relative to the core wire 250 or byadvancing the core wire 250 relative to the delivery catheter 102. Oncethe neck bridge 308 is unconfined outside the delivery catheter 102, itassumes an unfolded configuration. FIG. 18B shows the neck bridge 308having been deployed and placed within the aneurysm 306.

[0071] Next, one or more vaso-occlusive devices 314 may be deliveredinto the aneurysm using any of the conventional methods. (FIG. 18C) Ifthe neck bridge 308 includes a junction region 316 that has an opening,such as the opening 128 shown in FIG. 5, the vaso-occlusive device 314may be delivered via the inner tubular member 104, through the opening128 of the junction region 316 of the neck bridge 308, and into theaneurysm 306. It should be noted that instead of vaso-occlusive devices,other occlusion substance such as occlusion fluid or occlusion particlesmay also be delivered through the opening of the junction region 316 andinto the aneurysm 306. If the junction region 316 of the neck bridge 308does not have an opening, such as the embodiment shown in FIG. 16 or 17,the vaso-occlusive device 314 may be delivered to the aneurysm 306 alonga path that is exterior to the tubular member 104 or to the core wire250 if one is used. In this case, the neck bridge 308 should be madesufficiently flexible to distend around the vaso-occlusive deliverydevice. Alternatively, the vaso-occlusive device 314 may be deliveredinto the aneurysm 306 by going through an opening in the cover, such asa pre-made opening, or an opening defined by the fibers making up thecover. The vaso-occlusive device 314 may also be delivered into theaneurysm by puncturing the cover of the neck bridge 308.

[0072] After a desired number of the vaso-occlusive coils 314 have beenplaced in the aneurysm 306, the electrolytically severable joint 122 (orjoint 129, 140, or 252) is then severed, thereby de-coupling the neckbridge 308 from the tubular member 104 or from the core wire 250 if oneis used. (FIGS. 18D and 18E) The delivery catheter 102 and the innertubular member 104 are then withdrawn, leaving the vaso-occlusive device314 in place within the aneurysm 306. As shown in FIG. 18E, the neckbridge 308 stabilizes the presence of the vaso-occlusive device 314 andprevents the vaso-occlusive coil 314 from being drawn or escaping intothe feed vessel. If desired, a stent or a perfusion balloon mayoptionally be placed in the parent vessel to help seat the neck bridge308 within the aneurysm 306.

[0073] It should be noted that the neck bridge may also be placedoutside the neck of an aneurysm. FIGS. 19A-19C show another variation ofthe neck bridge 400 having a junction region 402, a number of radiallyextending array elements 404, and a cover 406. Unlike the previouslydescribed embodiments, the neck bridge 400 also includes a cage 408 madeup of a plurality of, e.g., platinum or nickel-titanium coils or wires409. A connector 410 connects the cage 408 to the junction region 402 orto the array elements 404, and is situated within the neck of theaneurysm after implantation. The array elements 404 are typically joinedto a releasable joint, which may be an electrolytically severable jointas discussed previously. As may be seen from FIG. 19B, the cage 408extends outwardly from the general center-line of the device andgenerally should be sized to conform to the size of, and generally tothe shape of, the aneurysm. FIG. 19C shows the general placement of thedevice within an aneurysm 414. The cage 408, which is within the sac ofthe aneurysm 414, anchors the cover 406, which is placed outside theneck of the aneurysm 414. The method of using the neck bridge 400 issimilar to that described previously with reference to FIGS. 18A-18E.

[0074] Many alterations and modifications may be made by those ofordinary skill in this art, without departing from the spirit and scopeof this invention. The illustrated embodiments have been shown only forpurposes of clarity and the examples should not be taken as limiting theinvention as defined in the following claims, which are intended toinclude all equivalents, whether now or later devised.

What is claimed:
 1. A device for bridging a neck of an aneurysm,comprising: a junction region; one or more radially extending arrayelements secured to the junction region, each array element having anunfolded shape and a delivery shape; and a cover attached to thejunction region, an array element, or both, wherein the cover extendsover the delivery shape of one of the array elements.
 2. The device ofclaim 1, wherein the junction region comprises a tubular section.
 3. Thedevice of claim 1, wherein each array element comprises a wire having acurvilinear shape.
 4. The device of claim 1, wherein each array elementcomprises a wire loop.
 5. The device of claim 4, each array elementhaving first and second ends attached to the junction region.
 6. Thedevice of claim 1, further comprising a tip, wherein array elementcomprises a wire having a first end attached to the tip and a second endattached to the junction region.
 7. The device of claim 6, the tiphaving an opening through which a vaso-occlusive device or occlusionfluid may be delivered.
 8. The device of claim 1, further comprising aradio-opaque marker carried on an array element.
 9. The device of claim8, wherein the radio-opaque marker is carried at a perimeter of thedevice.
 10. The device of claim 1, wherein the array elements eachcomprises a resilient, substantially elastic material.
 11. The device ofclaim 1, wherein the cover comprises a plurality of loops.
 12. Thedevice of claim 1, wherein the cover comprises an elastic material. 13.The device of claim 1, wherein the cover comprises polymer.
 14. Thedevice of claim 1, wherein the cover comprises polyester.
 15. The deviceof claim 11, wherein each loop comprising a fiber having first andsecond ends attached to the junction region.
 16. The device of claim 1,wherein the cover is attached to the array elements by an adhesive. 17.The device of claim 1, wherein the array elements are inter-woven withthe cover.
 18. The device of claim 1, wherein the cover has a top sideand a bottom side, and wherein the array elements are positioned betweenthe top side and the bottom side of the cover.
 19. The device of claim18, further comprising a disk positioned between the top side and thebottom side of the cover.
 20. The device of claim 1, further comprisingan elongate member detachably coupled to the junction region, theelongate member having a proximal end and a distal end.
 21. The deviceof claim 20, wherein the elongate member has a tubular cross section.22. The device of claim 20, wherein the elongate member comprises a corewire.
 23. The device of claim 20, wherein the elongate member carries aradio-opaque marker at one or both of its proximal end and distal end.24. The device of claim 1, wherein the cover is attached only to one ormore of the array elements.
 25. The device of claim 1, wherein the coveris attached only to the junction.
 26. A device for bridging a neck of ananeurysm, comprising: a junction region; and a radially extendingbraided structure secured to the junction region, the braided structuremade from an elastic material and having a delivery shape and anunfolded shape, the braided structure configured to be placed within theaneurysm.
 27. The device of claim 26, wherein the junction regioncomprises a tubular section.
 28. The device of claim 26, wherein thebraided structure comprises a plurality of loops.
 29. The device ofclaim 28, each loop comprising a fiber having first and second endsattached to the junction region.
 30. The device of claim 29, thejunction region including a first portion and a second portion, thefirst end of each loop attached to the first portion, the second end ofeach loop attached to the second portion.
 31. The device of claim 26,further comprising a radio-opaque marker carried on the braidedstructure.
 32. The device of claim 26, wherein the braided structure isplated or coated with a radio-opaque material.
 33. The device of claim26, wherein the braided structure comprises a radio-opaque material. 34.The device of claim 26, further comprising an elongate member detachablycoupled to the junction region, the elongate member having a proximalend and a distal end.
 35. The device of claim 34, wherein the elongatemember has a tubular cross section.
 36. The device of claim 35, whereinthe elongate member comprises a core wire.
 37. The device of claim 34,wherein the elongate member carries a radio-opaque marker at one or bothof its proximal end and distal end.